Metadata handling of ProSe Direct Discovery in the application of Proximity-based Service (ProSe) has been a topic under discussion. ProSe refers to an established Third Generation Partnership Project (3GPP) term which refers to device-to-device (D2D) discovery and communications. In case of Prose, communications takes place directly between two devices that are in proximity to each other without having an intermediary device delivering data in between. The stage 2 ProSe specification as described in 3GPP technical specification TS 23.303 defines two ProSe direct service types which are ProSe Direct Discovery and ProSe Direct Communication as well as two direct discovery types which are Open ProSe and Restrict ProSe Discovery. TS 23.303 is incorporated by references for the entirety of this document for the definition of terms and concepts.
According to TS 23.303, ProSe Direct Discovery refers to a procedure employed by a ProSe-enabled UE to discover other ProSe-enabled UEs in its vicinity by using only the capabilities that are common to the two UEs with E-UTRA technology. Restricted ProSe Direct Discovery refers to ProSe Discovery that would only take place with explicit permission from another ProSe-enabled UE that was discovered by a ProSe-enabled UE. Open ProSe Direct Discovery refers to ProSe Discovery that takes place without explicit permission from another ProSe-enabled UE that was discovered by a ProSe-enabled UE. Also described in TS 23.303 is Metadata which refers to data corresponding to the ProSe Application ID or Restricted ProSe Application User ID such as a postal address, phone number, URL, and etc. Moreover, Announcing UE refers to an UE that wants to spread certain information or to announce certain information such as a restaurant wanting to make itself known and to make known its menu. A monitoring UE refers to an UE that wants to monitor information being spread, such as a person looking for a restaurant or a restaurant menu.
The current state of the art mechanism as described in TS 23.303 without the adopted solution described in 3GPP technical document S2-152320 would define that the Home Public Land Mobile Network (HPLMN) ProSe Function of the monitoring UE would obtain the metadata with the optional Authentication Request/Response procedure as described in steps 4a and step 4b of the Match Report procedures which are also described in TS 23.303. However, TS 23.303 does not actually specify when the procedure of obtaining the metadata with the optional Authentication Request/Response is executed. Thus, if the ProSe Function does not send the Authentication Request, the ProSe Function would not be able to obtain the metadata and hence cannot send the metadata to the Monitoring UE.
To describe in more detail, refer to FIG. 1 which illustrates a Match Report procedure according to TS 23.303. In step S101, a ProSe enabled UE would transmit to a ProSe Function a Match Report with parameters including but not limited to a UE identity, a Discovery Type, an Application ID, a ProSe Restricted Code, and so forth. In step S102, in response to receiving the Match Report, the ProSe Function would perform discovery authentication. In step S103, the ProSe Function may perform an analysis of the received Prose Restricted Code. In step S104a, the ProSe Function may optionally transmit an Authentication Request to the ProSe application server. In S104b, the ProSe Function may optionally receive from the ProSe application server an Authentication Response which may include a field containing metadata. After a verification procedure of step S104c, in step S105, the ProSe Function may transmit to the ProSe enabled UE a Match Report Acknowledgment which may include the metadata.
Based on the procedure of FIG. 1, it can be seen that the metadata might not be delivered to the ProSe enabled UE since step S104a and step S104b are optional steps which may or may not be executed. If the ProSe Function does not send the Authentication Request in the first place, the ProSe Function will not be able to obtain the Metadata in order to send it to the ProSe enabled UE which could be a monitoring UE. Also, the current state of the art mechanism described in TS 23.303 does not actually define a mechanism to enable an Announcing UE learn if the ProSe Function has delivered the Metadata to a certain Monitoring UE. Moreover, the current state of the art mechanisms described in TS 23.303 also does not define a method to allow the Announcing UE to request a Metadata Delivery Receipt and to allow the Monitoring UE to block a Metadata Delivery Receipt to the Announcing UE.